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A Case Study on Adjacent Impact Zoning and Control Measures for New Double-line Shield Tunnel Undercrossing Existing Tunnel
(1. Key Laboratory of Transportation Tunnel Engineering, Ministry of Education, Southwest Jiaotong University, Chengdu 610031;2. School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031; 3. The First Engineering Company of CCCC Forth Harbor Engineering Co., Ltd., Guangzhou 510310)
Abstract In order to explore the impact of new undercrossing tunnel on the existing tunnel structure under differ? ent adjacent degrees, based on the Chengdu Subway Line 30 undercrossing the existing Jinxiu Tunnel on ChengduZigong High Speed Railway, the expression for adjacent impact degree is proposed by the theoretical research method, and the impact zoning control standard is determined by the structural displacement discrimination criteria. Numerical simulation and regression analysis methods are used to quantify and zone the adjacent impact range of the undercrossing construction, and targeted control measures are proposed for different impact zoning. The results show that the maximum settlement of existing tunnel segments is negatively correlated with the net distance between the newly-built tunnel and the existing tunnel, as well as the separation distance between left and right lines of the newly-built tunnel. A "gate" type protection structure is proposed for construction in the strong impact zone, which can reduce the maximum settlement of existing tunnel segments by 77.10%. For construction in weak impact zones,grouting reinforcement is proposed behind new tunnel segment walls, which can reduce the maximum settlement of existing tunnel segments by 56.86%. The monitoring results indicate that reasonable construction control measures can effectively control the displacement of the existing tunnel structure, and control the maximum settlement of the existing tunnel segment within the warning value of 6 mm.
Abstract：
In order to explore the impact of new undercrossing tunnel on the existing tunnel structure under differ? ent adjacent degrees, based on the Chengdu Subway Line 30 undercrossing the existing Jinxiu Tunnel on ChengduZigong High Speed Railway, the expression for adjacent impact degree is proposed by the theoretical research method, and the impact zoning control standard is determined by the structural displacement discrimination criteria. Numerical simulation and regression analysis methods are used to quantify and zone the adjacent impact range of the undercrossing construction, and targeted control measures are proposed for different impact zoning. The results show that the maximum settlement of existing tunnel segments is negatively correlated with the net distance between the newly-built tunnel and the existing tunnel, as well as the separation distance between left and right lines of the newly-built tunnel. A "gate" type protection structure is proposed for construction in the strong impact zone, which can reduce the maximum settlement of existing tunnel segments by 77.10%. For construction in weak impact zones,grouting reinforcement is proposed behind new tunnel segment walls, which can reduce the maximum settlement of existing tunnel segments by 56.86%. The monitoring results indicate that reasonable construction control measures can effectively control the displacement of the existing tunnel structure, and control the maximum settlement of the existing tunnel segment within the warning value of 6 mm.
FAN Wenhao1,
2 XIE Shenghao1,
2 ZHOU Feicong1 etc
.A Case Study on Adjacent Impact Zoning and Control Measures for New Double-line Shield Tunnel Undercrossing Existing Tunnel[J] MODERN TUNNELLING TECHNOLOGY, 2023,V60(4): 43-57
2023, Vol. 60 